The present invention relates to a biological signal measuring apparatus in which, while maintaining performance such as a noise processing function, the power consumption can be reduced and a long-term continuous use is enabled.
As one example of a biological signal measuring apparatus, a pulse oximeter which non-invasively measures the oxygen saturation of arterial blood is widely used (for example, see Patent Reference 1). In a measurement of the oxygen saturation by a conventional pulse oximeter, a probe is first attached to the tip of a finger or ear lobe of the subject, and the attached portion of the subject is illuminated in a time sharing manner with light beams of two different wavelengths or a red light beam and infrared light beams emitted from the probe. In the illuminating light beams, the transmitted light beam which is transmitted through the tissue of the finger tip or the ear lobe, or the reflected light beam which is reflected by the inside and outside of the tissue is detected for each of the wavelengths. The oxygen saturation is calculated from a ratio of pulsation components of absorbances obtained from the result of the detection.